Drawing board and t-square



Nov. 3, 1970 R. J. ANDERSON 3,537,183

DRAWING BOARD AND T-SQUARE Filed Feb. 17, 1969 j yv vroe I k I Ray J.fl/voszso/v J w/W United States Patent 3,537,183 DRAWING BOARD ANDT-SQUARE Roy J. Anderson, 1220 Crenshaw Blvd., Los Angeles, Calif. 90019Filed Feb. 17, 1969, Ser. No. 799,778 Int. Cl. B431 13/02 U.S. CI. 33-761 Claim ABSTRACT OF THE DISCLOSURE A drawing board and T-squarecombination in which the drawing board has an upwardly facing channelextending along a side edge, the T-square having a head provided withlugs spaced laterally of the blade of the T- square and slidable in thechannel for maintaining a right angular relation between the T-squareblade and the channel. A locking device is carried by the T-square head,the locking device including a clamping plate having an end disposed inthe channel in the board and a portion engaged by a pivoted cam, wherebythe clamping plate is actuatable into engagement with one side of thechannel to force the lugs on the T-square head into engagement with theother side of the channel.

Heretofore, drawing board and T-square combinations have been providedwherein the T-square head is adapted to be clamped or locked in aselected position of adjustment along an edge of the drawing board. Suchprior combinations for the most have been relatively complex and,therefore, expensive to produce, on the one hand, or, on the other hand,the clamping devices have been such that the T-sqnare may not bepositively and immovably held in a selected position upon operation ofthe clamping means.

In order to overcome the deficiencies of the prior art drawing board andT -square combinations and to provide a structure which is simple in itsoperation, yet positive in its locking action, the present inventionprovides a T- square and drawing board combination in which the drawingboard is provided along one edge with an elongated channel havingopposing, parallel side Walls between which lugs provided beneath thehead of the T-square are snugly, yet freely, slidable, whereby to allowshifting of the T-square along the work surface of the drawing board,while holding the T-square blade in right angular relationship to thechannel. The T-square head includes a clamp mechanism having a memberengageable with one side wall of the channel and forcing the lugscarried by the T-square head into engagement with the other side wall ofthe channel, whereby the T-square head is positively and immovably heldagainst angular movement by three-point engagement between the sidewalls of the channel on the board and the lugs and the clamping memberon the T- square head.

In accomplishing the foregoing, the present invention provides acam-operated locking mechanism involving a simple slidable plate havinga first end flange engageable in the channel of the drawing board, and asecond portion engageable by a pivoted cam member which locks the platein position with the T-square immovably held in relation to the drawingboard.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense.

See

Referring to the drawings:

FIG. 1 is a view in perspective illustrating a drawing board andT-square made in accordance with the invention;

FIG. 2 is an enlarged top plan illustrating the T-square in lockedcondition with respect to the drawing board;

FIG. 3 is an enlarged fragmentary detail view in section, taken on theline 3-3 of FIG. 2;

FIG. 4 is a fragmentary top plan illustrating the T- square head in anunlocked condition; and

FIG. 5 is an enlarged fragmentary detail view in section, taken on theline 55 of FIG. 4.

As seen in the drawings, the invention contemplates a drawing board B,herein illustrated as a simple rectangular drawing board, but it will beunderstood that the board B may form part of a drafting table. Forreference purposes, the board B will be seen to have an upper edge 1, alower edge 2, a right-hand edge 3, and a left-hand edge 4. Extendinglongitudinally in parallel relation to the lefthand edge 4 of the boardB is a channel 5. In the illustrative embodiment, the board B is shownas being the usual wooden drawing board in which the channel 5 isformed, and seated in the channel 5 is a metallic channel-shaped liner 6having a left-hand side wall 7 and a right-hand side wall 8 disposed inparallel relation to one another and effectively defining the side wallsof the channel 5. Preferably, the left-hand edge 4 of the drawing boardB is a straight edge paralleling the channel-shaped member 6 so that, ifdesired, the usual T-square may be employed .and engaged with the edge 4for performing work on a work sheet 9, which, as is customary, may besuitably secured to the work surface of the board B by thumbtacks 10,or, otherwise, as by adhesive tape or the like.

In accordance with the present invention, a T-square S is provided, thisTsquare including a head 11 and a blade 12 extending at right angleswith respect to the head 11 and having a straight lwork edge 13. In theillustrative embodiment, the blade 12 and the head 11 are shown as beingof unit construction, but it will be understood that, as is usual, thehead may be attached to a separate blade. In any event, the head 11 hasend portions 14 and '15 projecting laterally with respect to the blade12, and, adjacent the outer extremity of these portions 14 and 15, theyare respectively provided with downwardly extended lugs or projections14a and 15a, each of which is shown as being in the form of arectangular block depending from the T-square head and snugly butslidably engaged between the side walls 7 and 8 of the channel-shapedmember 6. These lugs 14a and 15a serve to maintain the proper rightangular relation between the channel-shaped member 6 and the blade 12 ofthe T square S, as the T-square assembly is moved upwardly anddownwardly with respect to the work sheet 9 on the drawing board B.

However, when it is desired that substantial drawing work be done on thework sheet 9 using implements such as triangles in conjunction with thework edge 13- of the T-square blade 12, it is desirable that the "blade12 be immovably held with respect to the drawing board B, to free bothhands of a person for use. Thus, clamping or locking means L areprovided for effectively clamping the T-square head 11 in fixed relationto the drawing board B, whereby the blade 12 is held in the desiredfixed relation to the work sheet 9. This locking or clamping means Lincludes a clamp plate -16 having a horizontally extended body portion17 slidably disposed in a groove 18 formed in and beneath themid-section of the T-square head 11. A suitable fastener 19 is employedto secure the body portion 17 of the clamp plate 16 in the groove 18,this fastener extending upwardly through the plate 16 and through anelongated slot 20 in the T-square head 11, the fastener 19 having a head21 of a greater dimension than defining with the body section 17 achannel-shaped portion 25 which receives a reduced thickness section 26of the T-square head 11. Preferably, the end flange 22 of the clampplate 16 is recessed within a depression 27 in the mid-section of theT-square head 11.

In order to eifect clamping movement of the clamp plate 16, a lever orcam 28 is provided, the lever being pivotally connected to a pivot pinor shoulder bolt 29 v which is threaded, as at 30, into the T-squarehead 11. The lever is provided with an operating handle 31 at one end,and, at the other end, the lever 28 has a downwardly extended cam pin 32which extends downwardly into the recess 27 so as to be engageable withthe inner edge 24a of the end flange 24 of the clamp plate 16. As seenin FIG. 2, the lever handle 31 may be rotated in a counterclock: wisedirection so that the camming action of the lever pin 32 sliding alongthe edge 24a of the end flange 24 of the clamp plate 1 6 will force theclamp plate 16 to the left, thereby forcing the inner end flange 22 ofthe clamp plate 16 into frictional engagement with the outer side wall 7of the channel-shaped member 6, resulting in the inner side walls 14band 15b of the lugs 14a and 15a being forced oppositely into engagementwith the inner side wall 8 of the channel-shaped member 6. Preferably,as seen in FIG. 2, the cam pin 32 moves to a position at which its axisis on a plane normal to the cam surface 24a and intersecting the axis ofthe pivot pin 29, whereby the plate 16 is locked in a clamping positionby the lever 28.

Since the lugs 14a and 15a are laterally spaced with respect to theT-square blade 12, and since the clamp plate 16, and more particularlyits flange 22, is centrally located with respect to the T-squarehead 11,the clamping action is such that the T-square head 11 will be immovablyand positively held against movement with respect to the drawing boardB. While spaced apart lugs have been illustrated and are preferred, itwill be understood that the essential feature of the locking means ofthe invention is the opposite application of clamping face of the boardB, to position the blade 12, and more particularly the work edge -13thereof, in a desired and selected position with respect to the worksheet 9. Under these circumstances, the lever 28 will be in thecondition illustrated in FIGS. 4'and 5 in which the inner end flange 22of the clamp plate 16 is spaced from the side wall 7 of thechannel-shaped member 6, the lugs 14a and 15a being free to slide alongthe channel-shaped member 6. When substantial ,work is to be done withimplements, such as triangles or protractors, at any selected locationof the T-square S, or where the use of both hands is necessary ordesirable, the T-square S may be locked in the selected position bysimply rotating the lever 28 to the position shown in FIGS. 2 and 3, atwhich the end flange 22 of the clamp member '16 engages the side wall 7of the channelshaped member 6, and the faces 14b and 15b of the lugs 14aand 15a are forced against the side wall 8 of the channel-shaped member6.

I claim:

1. A drawing board and T-square combination comprising: a drawing boardhaving an elongated channel at one edge thereof, said channel havingopposed parallel side walls, and a T-square slidably disposable uponsaid 1 board and including a head and a blade projecting from said headin overlying relation to said board, said head having guide meansslidable in said channel for maintaining said blade in right angularrelation to said channel, lock means cooperative with said guide meansfor re- 7 leasably clamping said head in a fixed position with rein saidgroove, and operating means carried by said head forces between aclamping member, such as the member In the use of the drawing board andT-square as de- I scribed above, it will be understood that in normalusage the clamping or locking means L may be released so that theT-square S is easily slidable along the upper surand-acting on saidanother flange for sliding said clamp plate to move said first-mentionedflange into engagement with a side wall of said channel and to forcesaid guide means into engagement with the other side wall of saidchannel, said operating means including a lever pivotally mounted onsaid head and-having a cam pin engageable with a surface of said anotherflange of said clamp plate for shifting said clamp plate responsive topivotal movement of said lever, said cam pin and the axis of pivotalmovement of said lever being in a plane at least normal to said surfacewhen said lock means is operated to clamp'said T-square to said channel.

, References Cited UNITED STATES PATENTS 2s2,24s 7/1 883 Weidenmann33-76 1,020,253 3/1912 Blair 3376 1,593,097 7/1926 0rd 33--76 FOREIGNPATENTS 493,735 6/1950 Belgium.

HA'R-RY N. HAROIAN, Primary Examiner

